Development of nitric oxide releasing nano-system for 3D printed regenerative vascular grafts

info:eu-repo/semantics/publishe

Investigation on Amount of Secreted Nitric Oxide from Endothelial Cells by Applying Shear Stress and Different Temperature

status: publishe

Carbon nanotubes as a nitric oxide nano-reservoir improved the controlled release profile in 3D printed biodegradable vascular grafts

Abstract Small diameter vascular grafts (SDVGs) are associated with a high failure rate due to poor endothelialization. The incorporation of a nitric oxide (NO) releasing system improves biocompatibility by using the NO effect to promote endothelial cell (EC) migration and proliferation while preventing bacterial infection. To circumvent the instability of NO donors and to prolong NO releasing, S -nitroso- N -acetyl- d -penicillamine (SNAP) as a NO donor was loaded in multi-walled carbon nanotubes (MWCNTs). Successful loading was confirmed with a maximum SNAP amount of ~ 5% (w/w) by TEM, CHNS analysis and FTIR spectra. SDVGs were 3D printed from polycaprolactone (PCL) and coated with a 1:1 ratio of polyethylene glycol and PCL dopped with different concentrations of SNAP-loaded matrix and combinations of MWCNTs-OH. Coating with 10% (w/w) SNAP-matrix-10% (w/w) SNAP-MWCNT-OH showed a diminished burst release and 18 days of NO release in the range of 0.5–4 × 10 –10  mol cm −2  min −1 similar to the NO release from healthy endothelium. NO-releasing SDVGs were cytocompatible, significantly enhanced EC proliferation and migration and diminished bacterial viability. The newly developed SNAP-loaded MWCNT-OH has a great potential to develop NO releasing biomaterials with a prolonged, controlled NO release promoting in-situ endothelialization and tissue integration in vivo ,even as an approach towards personalized medicine.info:eu-repo/semantics/publishe

Additively manufactured small-diameter vascular grafts with improved tissue healing using a novel SNAP impregnation method

The vascular network has a complex architecture such as branches, curvatures, and bifurcations which is even more complicated in view of individual patients' defect anatomy requiring custom-specifically designed vascular implants. In this work, 3D printing is used to overcome these challenges and a new shorter impregnation method was developed to incorporate S-nitroso-N-acetyl-d-penicillamine (SNAP) as a nitric oxide (NO) donor to printed grafts. The 3D-printed small-diameter vascular grafts (SDVGs) were impregnated with SNAP solution during SNAP synthesis (S1) or with SNAP dissolved in methanol (S2). The advantage of the newly developed S1 impregnation method is the elimination of the synthesis step by direct impregnation inside the S1 solution. Scanning electron microscopy imaging reveals the successful crystal formation in both methods. The results demonstrate that both S1- and S2-impregnated grafts, after covering with polycaprolactone topcoat, can release NO in a controlled manner and in the physiological range (0.5-4.0 × 10-10 mol cm-2 min-1 ) over a 15 days period. The created grafts with a NO-releasing surface have also shown bactericidal effect while the healing properties of the implant were improved by promoting migration and proliferation of endothelial cells (ECs). These results suggest that incorporation of 3D printing technology with the newly developed S1 impregnation of SNAP can optimize and shorten the manufacturing process of the next generation of patient-based antibacterial SDVGs with a higher attraction for ECs.status: publishe

Nitric oxide secretion by endothelial cells in response to fluid shear stress, aspirin, and temperature

Current vascular grafts have a high incidence of failure, especially in the grafts less than 6 mm in diameter, due to thrombus formation. Nitric oxide (NO) is released by endothelium and has some beneficial influences such as an antithrombotic effect. We hypothesized that applying different shear stress regiments and low temperature or aspirin would result in an increase in the amount of NO release from human umbilical vein endothelial cells (HUVECs) and decrease in platelet aggregation in the same manner as expected in vivo. HUVECs were cultured into the intraluminal surface of silicone tubes. HUVECs were subjected for 60 min to different parameters of shear stress, temperature, aspirin, and platelets or a combination in a perfusion bioreactor by monitoring NO secretion. We found that shear stress leads to an elevation of NO production in HUVECS, independent of the shear stress magnitude (0.9 or 1.8 dyne/cm2). The magnitude of this response increased with a decrease in temperature. Our results also show that by addition of platelets in combination with aspirin to media circulation, no thrombus formation occurred during the test time. Presence of aspirin resulted in marked increase in NO levels. In conclusion, shear stresses, temperature lowering, and aspirin increase the amount of NO release from HUVECs. Also no thrombus formation was detected in our experimental setting

Controlled NO-release from 3D-printed small-diameter vascular grafts prevents platelet activation and bacterial infectivity

status: accepte